1. Field of the Invention
The present invention relates to a color CRT Cathode Ray Tube), and more particularly, to a color CRT panel which forms a front surface of a CRT for displaying an image.
2. Background of the Related Art
The CRT forms an important part for displaying an image thereon in a display, such as a TV receiver or a computer monitor. FIG. 1 illustrates a side view inclusive of a partial section of a color CRT.
Referring to FIG. 1, there is a fluorescent film 1a on an inside surface of a panel 1 which forms a front surface of the CRT having red, green and blue fluorescent materials coated thereon, a funnel 2 at rear of the panel 1 frit glass welded to the panel 1, and an electron gun 4 provided in a neck portion 2a of the funnel 2. And, there is a shadow mask 5 fastened to a frame 6 close to the fluorescent film 1a on an inner side of the panel 1 for selecting a color of electron beams 3. The frame 6 is hung from the sidewall of the panel 1 by a support spring 8 having one end fastened thereto and the other end inserted to a stud pin 1b fastened to a sidewall of the panel 1. And, there is an inner shield 7 fastened to the frame 6 by a fastening spring on one side of the frame 6 for protecting the electron beams 3 traveling toward the fluorescent film 1a from an external geomagnetic field. There is a deflection yoke 10 attached to an outer circumferential surface of the neck portion 2a having a plurality of poles for correcting a locus of travel of the electron beams 3 so that the electron beams 3 exactly hit a desired fluorescent material, and a reinforcing band 9 on an outer circumferential surface of the CRT for preventing breakage of the CRT from an external impact during operation of the CRT. Within a basic structure of the CRT, the shadow mask 5, formed to have a required curvature and disposed to have a required space from the panel 1, forms a panel assembly with the panel, so that the three electron beams 3 emitted from the electron gun 4 exactly hit onto the fluorescent material on an inside surface of the panel through the shadow mask 5, to reproduce an image. Accordingly, an accurate curvature design of the shadow mask 6 is required for implementing an exact image, for which an inner curvature of the panel 1 is considered as a precondition of the curvature design.
FIG. 2 illustrates a cross section of a panel assembly, referring to which a relation between a panel inside surface curvature and a curvature of the shadow mask will be explained.
Referring to FIG. 2, the panel 1 has an inside/an outside curved surfaces, radius Ro of the outside surface and radius Ri of the inside surface have Ro greater than Ri relation, for withstanding a force caused by a pressure difference between the atmospheric pressure and a high vacuum in a Braun tube. The inside surface curvature Ri of the panel 1 is considered to be the most important factor for determining a curvature of the shadow mask 5, and the curvature of the shadow mask 5 determined herein has close relations with a structural strength, and thermal deformation characteristics of the shadow mask 5. As shown in FIG. 3, the inside surface curvature Ri of the panel 1 has an arc curvature shown in a solid line and a super arc curvature shown in dashed line. The super arc curvature exhibits a height displacement of the shadow mask less than the arc curvature, according to which the super arc curvature is effective to a thermal deformation of the shadow mask 5. Accordingly, through the arc curvature and the super arc curvature are applied to the related art CRT without any particular distinction, the super arc curvature is used more when a thermal deformation characteristic is taken into consideration. Currently, the outside surface curvature Ro is designed to be greater than 40,000 mm for forming the outside surface of the panel 1 to be flat perfectly or close to the perfect flat, which causes the inside surface curvature Ri dependent on the outside surface curvature Ro of the panel 1, together with an increase a curvature of the shadow mask 5 which is dependent on the inside surface curvature Ri. As explained, the greater the curvature of the shadow mask 5, though the more effective to a thermal deformation, the worse to a strength of the shadow mask 5. Accordingly, howling is occurred, in which an image is shaken by an impact, or speaker sound, and a poor color reproducibility is caused, in which a color of the image is changed partially. Currently, since the thermal deformation is solved, not by a method of the curvature of the shadow mask 5, but by other method, i.e., by a method in which a reflection film (not shown) is coated on a surface the electron beams 3 hit thereon for reflecting thermal ions, a method for reinforcing the structural strength of the shadow mask is required.
Accordingly, the present invention is directed to a color CRT panel that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a color CRT panel which has a structure of an inside surface curvature that can reinforce a structural strength of the shadow mask.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the color CRT panel includes an outside surface substantially flat, and an inside surface with a desired curvature, wherein an inside surface curvature structure of the panel consists of arc curvatures having a long axis direction radius Rx of curvature and a short axis direction radius Ry of curvature different from each other.             T      c        +          (                        R          y                -                                            R              y              2                        -                          L              ye              2                                          )            T    c  
is within a range greater than 1.5 and smaller than 2.5, where,       R    y    =                              L          ye          2                +                  Z          ye          2                            2      xc3x97              Z        ye            
Tc denotes a thickness of a center portion of the panel,
Lye denotes a distance from the center portion of the panel to an end of an effective surface in a short axis direction, and
Zye denotes a height at the end of the effective surface in the short axis direction.
Rx/Ry is preferably within a range of 2.2-2.8.
Fxe2x80x2(r)=(a+bxc2x7R+cxc2x7R2)xc2x7rxc2x1(d+exc2x7Le+fxc2x7Le2), and Fxe2x80x2(r)=(a+bxc2x7Rx+cxc2x7Rx2)xc2x7rxc2x1(d+exc2x7Lxe+fxc2x7Lxe2), when xe2x80x98rxe2x80x99 is on the long axis (X-axis), and Fxe2x80x2(r)=(a+bxc2x7Ry+cxc2x7Ry2)xc2x7rxc2x1(d+exc2x7Lye+fxc2x7Lye2), when xe2x80x98rxe2x80x99 is on the short axis (Y-axis), wherein the constants xe2x80x9ca, b, c, d, e, and fxe2x80x9d in both of Fxe2x80x2(r) for the long axis and the short axis have the following values.
a=1.17146Exe2x88x9203,
b=xe2x88x924.11994Exe2x88x9207,
c=4.53728Exe2x88x9211,
d=4.82475Exe2x88x9202,
e=xe2x88x922.36837Exe2x88x9204, and
f=3.78612Exe2x88x9207
The panel inside surface curvature meets a range of dispersion of the primary derivative Fxe2x80x2(r) dependent on the constants xe2x80x9ca, b, c, d, e, and fxe2x80x9d, a radius of curvature Rx or Ry, and a distance Lxe or Lye.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.